XLPE
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XLPE (Cross-linked polyethylene) is a kind of insulator which is used as insulation layer in underground power cables. XLPE (crosslinked polyethylene) is a thermoset material produced by the compounding of LDPE with a crosslinking agent such as dicumyl peroxide. Al Gilbert and Frank Precopio invented XLPE in March 1963 in the GE Research Laboratory located in Niskayuna, New York. In this process, the long-chain PE molecules “crosslink” during a curing (vulcanization) process to form a material that has electrical characteristics that are similar to thermoplastic PE, but with better mechanical properties, particularly at high temperatures.
XLPE-insulated cables have a rated maximum conductor temperature of 90oC and an emergency rating of up to 140oC, depending on the standard used to rate XLPE-insulated cables. Cables insulated with XLPE also have a conductor short-circuit rating of 250oC. XLPE has excellent dielectric properties making it useful for a large range of voltage applications from 600 V to 500 kV.
A number of modifications in the basic polymer structure can be made to maximize productivity during the cable manufacturing processes. In medium voltage applications, the reactivity can be boosted significantly. This results in higher line speeds in the cases where there are limitations in either the curing or cooling processes within the continuous vulcanization (CV) tubes used to crosslink the insulation. XLPE insulations can also be modified to limit the amount of by-product gases that are generated during the crosslinking process. This is particularly useful for high voltage and extra-high voltage cable applications, where degassing requirements can significantly lengthen the time required to manufacture the cable.
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| Polyethylene (PE) | Polypropylene (PP) | Polystyrene (PS) |
| Polyethylene terephthalate (PET or PETE) | Polyamide (PA) | Polyester |
| Polyvinyl chloride (PVC) | Polycarbonate (PC) | Acrylonitrile butadiene styrene (ABS) |
| Polyvinylidene chloride (PVDC) | Polytetrafluoroethylene (PTFE) | Polymethyl methacrylate (PMMA) |
| Polylactic acid (PLA) | ||
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